package com.example.springboot.utils;

import com.google.common.collect.Lists;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.BeanWrapper;
import org.springframework.beans.BeanWrapperImpl;
 
import java.util.HashSet;
import java.util.List;
import java.util.Set;
 
public class CopyObjectUtil {
        /**
         * @param input 输入集合
         * @param clzz  输出集合类型
         * @param <E>   输入集合类型
         * @param <T>   输出集合类型
         * @return 返回集合
         */
        public static <E, T> List<T> convertList2List(List<E> input, Class<T> clzz) {
            List<T> output = Lists.newArrayList();
            if (input != null && !input.isEmpty()) {
                for (E source : input) {
                    T target = BeanUtils.instantiate(clzz);
                    BeanUtils.copyProperties(source, target);
                    output.add(target);
                }
            }
            return output;
        }
 
 
        /**
         * @Description: 忽略null值/只拷贝非null属性
         */
    public static String[] getNullPropertyNames (Object source) {
        final BeanWrapper src = new BeanWrapperImpl(source);
        java.beans.PropertyDescriptor[] pds = src.getPropertyDescriptors();
 
        Set<String> emptyNames = new HashSet<String>();
        for(java.beans.PropertyDescriptor pd : pds) {
            Object srcValue = src.getPropertyValue(pd.getName());
            if (srcValue == null) emptyNames.add(pd.getName());
        }
        String[] result = new String[emptyNames.size()];
        return emptyNames.toArray(result);
    }
 
    public static void copyProperties(Object src, Object target) {
        BeanUtils.copyProperties(src, target, getNullPropertyNames(src));
    }
}
